Air is warmed and moisten as it moves through both the mouth and nasal passages.
a. true
b. false

The given statement is true.

Transport of oxygen from the air takes place through respiratory system. Oxygen from air ( that is taken from the atmosphere) enters via a system of tubes, into our lungs and then it is released into the bloodstream ( to serve in various organs) whereas opposite route is followed by CO2 ( carbon dioxide).

In the respiratory tract, the nose is lined by mucosal epithelium that possessed glands ( which secrete thick mucus). Due to this, air is moistened.  Beneath the epithelium surface, there lies  network of blood vessels that help in warming the nasal cavity and thus the air is warmed.

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